/Engine/Source/Developer/TextureFormat/Public/Interfaces/ITextureFormat.h
int32 GetNumStreamingMips ( const [FEncodedTextureExtendedData](API\Developer\TextureFormat\Interfaces\FEncodedTextureExtendedData) * InExtendedData, const [FTextureEngineParameters](API\Developer\TextureFormat\Interfaces\FTextureEngineParameters) & InEngineParameters ) const